Producing tungsten alloys



Patented Apr. 11,

UN TED STATES PAT/ENTY, err-ice I I rnonuomo 'fiitl s rnn annoys Arthur Linz, New York, N. Y., assignor to cu Molybdenum Company, New York, N. Y., a cor notation of Delaware No Drawing.

The present invention relates to alloying tungsten with ferrous metals and more particularly to a novel'and improved process and composition for introducing tungsten into steel during the alloying process. v

Objects and advantages of the invention will be setforth in part hereinafter and in-partwill riginal application January 18, 1940, Serial No. 314,447. Divided and this application December 12, 1941, Serial'No. 4.22.673

1 Claim. ons-13s) mixtureinto briquettes each of whichnay contain a uniform amount of tungsten.

In case only a portion of the desired amount of tungsten is added in the form of tungstic oxide be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the steps, processes and instrumentalities pointed out in the appended claim.

The invention consists in the novel steps, processes, combinations and improvements herein shown and described.

. the tungsten addition, the lower oxides of tung- Heretofore, tungsten-bearing ferrous. alloys have been commercially produced by adding calcium tungstate, ferro-tungsten' or some tungsten-bearing mineral such as wolframite, scheelite', fer-berite or hubernite to the molten steel. However, due to the relatively great specific gravity of ferro-tungsten, it tendsto sink in the molten steel and it is difflcult to dissolve and thereby obtain a homogeneous alloy. Many of the alloying materials also have the disadvantage that theyare absorbed only slowly into the steel bath, and at the same time introduce undesirable impurities..

In my prior parent application Ser. No. 314,447 filed January 18, 1940, now Patent No. 2,282,486, granted May 12, 1942, I have disclosed and claimed a process of producing tungsten alloys sten may be. employed alone or in combination with tungstic oxide, and where an alloy rich in tungsten is to be produced, this will be advantageous over using tungstic oxide as the boiling will be less vigorous and more easily controlled.

in which briquettes of tungstic oxide and pitch are added to the ferrous material, and after the tungsten has been absorbed into the steel, the.

chromium and vanadium is reabsorbed into the alloy from the slag by the addition of ferrosilicon. The present application is a division of my said application Ser. No. 314,447.

Such additions of ferrosilicon are not essential, where the alloy isproduced in an electric furnace andi's covered with a redficing or car-.

bide slag. Where the tungsten alloy steel is produced in an electric furnace, it is usual to cover the ferrous alloy with a reducing slag (carbide slag), and if that be the'case, the reduction of the tungstic or other tungsten; oxide not only renders the tungsten available for solution in the steel, but also tends to remove certain of the objectionable impurities from the steel. J

'ForcohVenience in handling, and in order to reducethe amount of oxidation caused by the tungsten oxide, it is preferably prepared for use by mixing it with some carbonaceous, reducing material, such as still-pitch, and by molding this 65.

Referring now in detail to the present preferred manner of carrying out the invention, the powdered tungstic oxide is mixed with about one tenth its weight of still-pitch, and this mixture is formedinto uniform briquettes each of which may'conveniently contain five pounds of tungsten. where lower oxides of tungsten are used, a lesser proportion of carbonaceous material maybe employed, enough being used, however, to completely reduce the oxide.

The alloying ingredients for the desired alloy, excluding only the tungsten oxide briquettes, are

charged inthe electric furnace, and brought to the proper temperature in the usual manner and covered with the usual carbide slag. Thereafter, after suflicient time has been allowed for the absorption of whatever ferro-tungsten may be used, the remainder of the tungsten requirements is added in the form of the tungsten oxide briquettes: As these are added, the power supplied tothe electric furnace may be controlled or reduced so as to control the heat of the mixture and to prevent too vigrous agitation or boiling" as the tungsten oxide is reduced.

- After the reduction of tungsten oxide has been completed, the heating of the alloy is continued. For usual tungsten alloys, the entire amount of tungsten may be supplied by tungstic oxide briquettes, but for larger amounts of tungsten and where tungstic oxide briquettes alone might,

cause'too vigorousboiling a part of the tugsten may be added in the form of ferro-tungsten as described above, or some .or all of the briquettes may be of one or more; of the lower 4 oxides of tungste these lower oxides producing less gas and a .less vigorous boiling of the molten metal.

A process of producing tungsten containing alloy steel in an electric furnace which comprises adding to the furnace charge ierro-tungsten to supply a portion ofthe required tung-- sten in the alloy,. and after the ferro-tungsten has been absorbed adding self-reducing briquettes, composed of a mechanical mixture of an oxide of tungsten and a carbonaceous reducing agent, through a carbide slagf covering theother molten alloying ingredients.

ARTHUR LIN Z.- 

